Composite cable units

ABSTRACT

A composite cable unit having an optical sub-unit including at least one optical fiber, and an electrical sub-unit including at least one electrical conductor for power or transmission. The optical and electrical sub-units are removably connected together by a common jacket material. The composite cable unit can be used singly or in, for example, fan-out or break-out cables.

RELATED APPLICATIONS

The present application is a Continuation of U.S. Ser. No. 09/220,268filed Dec. 23, 1998 now U.S. Pat. No. 6,323,192, which is incorporatedherein by reference.

The present invention relates to composite cables having combinedoptical and electrical power and/or transmission capabilities.

Conventional fiber optic cables include optical fibers that conductlight which is used to transmit voice, video, and data information.Conventional composite cables combine the advantages of opticaltransmission components, e.g., large bandwidth and low power loss, withthe advantages of electronic/electrical transmission components whichinclude low cost and straightforward termination procedures. Typicalapplications for composite cables include fiber-to-the-curb (FTTC),fiber-to-the-home (FTTH), fiber-to-the-desk (FTTD), plenum, riser, andlocal area networks (LANs). In a premises environment, composite cablescan be used to interconnect hardware, for example, computers andtelephones.

A conventional cable design is illustrative of transmission electricalcables. U.S. Pat. No. 5,681,179 discloses a conventional electrical zipcord with stranded electrical conductors only. The zip cord can beterminated with an electrical connector with relative ease, but thecable does not include optical transmission components.

Conventional composite cables can include a row of optical fibers and aseparate row of electrical conductors. For example, U.S. Pat. No.5,039,195 discloses a composite cable with two distinct cable units. Afirst cable unit includes optical fiber sub-units connected to strengthmembers by a common jacket having interconnecting web sections. A secondcable unit includes metal conductors connected by a common jacket havinginterconnecting web sections. Both cable units are surrounded by a cablejacket.

As disclosed in U.S. Pat. No. 5,602,953, a composite cable can include acombination of loose-buffered optical fibers and electrical conductorsin a common jacket. The common jacket defines a flat structure includingbox-shaped sub-units, apparently formed by an injection molding process,with twisted electrical leads and optical fibers disposed in buffertubes. The cable is designed to be separated into the box-shapedsub-units.

OBJECTS OF THE INVENTION

It is an object of the present invention to provide a composite cableunit having an optical sub-unit including at least one optical fiber,and an electrical sub-unit including at least one electrical conductor.The optical and electrical sub-units are removably connected together bya common jacket material.

It is an object of the present invention to provide a fan-out cablehaving a central member with cable units therearound. At least one ofthe cable units comprises a composite cable unit, the composite cableunit including an optical sub-unit with at least one optical fiber, andan electrical sub-unit including at least one electrical conductor, theoptical and electrical sub-units being removably connected together by acommon jacket material.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

FIG. 1 is a cross sectional view of a composite cable unit according tothe present invention.

FIG. 2 is a cross sectional view of the composite cable unit of FIG. 1surrounded by a protective sheath.

FIG. 3 is a cross sectional view of a fan-out cable having a compositecable unit according to the present invention.

FIG. 4 is a cross sectional view of a fan-out cable having a compositecable unit according to the present invention.

FIG. 5 is a cross sectional view of a composite cable unit according tothe present invention.

FIG. 6 is a cross sectional view of a composite cable unit according tothe present invention.

FIG. 7 is a cross sectional view of a composite cable unit according tothe present invention.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIGS. 1-6, low-cost composite cable units 10,20,30,according to the present invention for use in, for example, FTTC, FTTH,FTTD, plenum, riser, or LAN applications will be described.

Skilled artisans will appreciate that, in light of the presentdisclosure, fan-out cables and composite cable units made according tothe present invention can take various forms. For example, the presentinvention can be practiced as a composite cable unit 10 (FIG. 1) havingan optical sub-unit 1 connected to an electrical sub-unit 2. Opticalsub-unit 1 can include an optical fiber 12 therein, e.g., a 900 μm tightbuffered optical fiber. Optical fiber 12 can be surrounded by a layer ofstrength filaments 14, for example, aramid or fiberglass fibers thatde-couple optical fiber from a common jacket 18. Optical fiber 12 caninclude, for example, one or more single mode optical fibers, or one ormore multi-mode or multi-core optical fibers. Electrical sub-unit 2 caninclude one or more electrical conductors 16, for example, a twistedpair of electrical conductors 16. Electrical conductors 16 maypreferably be about 19 to 26 AWG or smaller.

Optical fiber 12 and electrical conductors 16 can be disposed withincommon jacket 18 formed of polyvinyl chloride (PVC), polyethylene (PE),a UV curable resin (e.g. acrylate), or a fluoro-compound. The materialof jacket 18 can include one or more flame retardant additives, forexample, tetrabromoethane, chlorinated paraffin, chlorinatedpolyethylene, tetrabromobisphenol A, and/or phosphate compounds.Inorganic flame retardant additives can be used as well, for example,magnesium compounds, antimony trioxide, and aluminum hydroxide. Flameretarding jacket 18 can be required for assuring satisfactory plenum(e.g. UL-910) or riser (e.g. UL-1666) cable burn performancecharacteristics. Sub-units 1,2 can be separably connected to each otherby extrusion or welding portions of jacket 18 together. Alternatively,sub-units 1,2 can be connected by a frangible ligature 17 duringextrusion of jacket 18. Ligature 17 can include separation areas 17 a,17b(FIGS. 1-3), for ease of separation of sub-units 1,2. Jacket 18 canalso include access recesses 18 a,18 b for separating jacket 18 to gainaccess to optical fiber 12. Composite cable unit 10 can be surrounded bya layer of strength fibers 15 and a protective sheath 19 (FIG. 2).Sheath 19 can be formed of PVC, PE, or a fluoro-compound, any of whichmaterials can include one or more flame retardant additives.

Further, the invention can be practiced in the form of a composite cableunit 20 (FIG. 3) having more than one twisted pair electrical conductors16, and a multi-core optical fiber 12'. Suitable exemplary multi-coreoptical fibers are disclosed in U.S. Pat. No. 4,000,416 and U.S. Pat.No. 5,222,172, both of which are incorporated by reference herein.Composite cable unit 20 can be part of a fan-out cable 40, and can belongitudinally disposed adjacent to, or helically (unidirectional) or SZstranded about, a central member 22. Central member 22 can be, forexample, a fiber or a glass reinforced plastic rod, or fibersimpregnated with a polymeric resin. Composite cable unit 20 can bestranded with other fiber optic components, for example, tight bufferedor loose buffered optical fiber components 24 or 26.

In addition, the invention can be practiced in the form of a compositecable unit 30 (FIG. 4), for example, having one or more composite cableunits 10,20 joined together by a ligature 17. Composite cable unit 30can be part of a fan-out cable 50 and can be stranded about a centralmember 22 along with other fiber optic components, for example, tightbuffered or loose buffered optical fiber units 24,26. Moreover, thepresent invention can be practiced in the form of a composite cable unit60 (FIG. 5) having a jacket 18 formed of a UV curable acrylate, PVC,polyurethane, or PE material. Cable 60 can be generally flat and canhave one or more conductors 16 that may be used to, for example, conductlow voltage electrical power.

Sub-units 1,2 can be formed with separate jacket layers 18 and thenjoined together by welding the portions of jacket 18 together. Theconductors 16 can be overcoated with a jacket 18 such that theinsulation of the conductors is separably adhered to jacket 18.Additionally, a controlled bond can be formed between jacket 18 and theinsulation of conductors 16 by passing the conductors through, forexample, a silicone bath or talc powder applicator prior to applicationof jacket 18. Electrical sub-unit 2 can be connected to sub-unit 1 byuse of a heated knife apparatus that welds the sub-units together.

Alternatively, sub-units 1,2 of the present invention can bemanufactured by passing the optical and electrical components through anextruder and extruding jacket 18 therearound. Prior to extrusion,filaments 14 can be coated with a talc powder to prevent sticking ofjacket 18 to the filaments. The die profile can be shaped so thatsub-units 1,2 have a generally round cross section, or other crosssectional shapes may be formed as well. The die can include a profilethat will result in the formation of ligatures area 17 a, 17 b, and/oraccess recesses 18 a,18 b. Ligature 17 b can include a web thicknessthat is less than the outside diameter (OD) of at least one of thesub-units. Ligature 17 b can space sub-units 1,2 apart a suitabledistance for easy separability. The respective outside diameters of thesub-units need not be equal.

A craftsman can easily separate the sub-units as desired, remove asection of jacket 18, and connectorize/terminate the fibers andelectrical conductors. Composite cable units of the present inventionadvantageously provide a combination of the benefits of optical andelectronic/electrical functionalities.

The present invention has thus been described with reference to theforegoing embodiments, which embodiments are intended to be illustrativeof the present inventive concepts rather than limiting. Persons ofordinary skill in the art will appreciate that variations andmodifications of the foregoing embodiments can be made without departingfrom the scope of the appended claims. For example, electrical conductor16 can be any suitable electrical transmission component, e.g., aco-axial cable or a non-twisted conductor. Filaments 14 can be smallimpregnated fibers or rods surrounding or adjacent to the optical fiber.Any of the composite cable units can be part of a break-out cable.Fan-out or break-out cables of the present invention can includestrength filaments adjacent to the cable units. Where wavelengthselection features are desired in the optical sub-unit, one or moreperiodic refractive indices can be written into the fiber beforebuffering, for example, as disclosed in U.S. Pat. No. 4,725,110, (U.S.Pat. No 5,620,495, U.S. P at. No. 5,718,738, and/or U.S. Pat. No.5,818,630, all of which are respectively incorporated by referenceherein. For identification purposes, a craftsman may be able todistinguish between the optical and electrical sub-units withoutidentification means; however, an identification means can be providedon either or both of the sub-units. The identification means can includedifferent colors for the sub-units, one or more extruded or inked-onstripes 13 (FIG. 2), or any other suitable identification means. Fan-outcables according to the present invention can include fiber optic cablecomponents, for example, ripcords or water blocking yarns. As shown inFIGS. 3 and 7, the optical sub-unit can include a buffer tube 21 withone or more optical fibers therein.

Accordingly, what is claimed is:
 1. A composite cable unit, comprising:an optical sub-unit, said optical sub-unit including a tube surroundingat least one optical fiber and strength members or filaments that areoperative to at least partially de-couple said at least one opticalfiber from said tube; an electrical sub-unit; and said optical andelectrical sub-units being removably connected at a medial portionbetween said sub-units by a common jacket material.
 2. The compositecable unit of claim 1, said at least one optical fiber being tightbuffered.
 3. The composite cable unit of claim 1, said at least oneoptical fiber including at least one periodic refractive index therein.4. The composite cable unit of claim 1, said at least one electricalconductor being part of a coaxial cable.
 5. The composite cable unit ofclaim 1, said common jacket material including a ligature connectingsaid sub-units.
 6. The composite cable unit of claim 1, said sub-unitsbeing separably welded together.
 7. The composite cable unit of claim 1,said common jacket material including at least one identification means.8. The composite cable unit of claim 1, a controlled bond being formedbetween said common jacket material and said at least one electricalconductor.
 9. A composite cable unit, comprising: an optical sub-unit,said optical sub-unit including a tube surrounding at least one tightbuffered optical fiber and strength members or filaments that areoperative to at least partially de-couple said at least one opticalfiber from said tube; an electrical sub-unit; and said optical andelectrical sub-units being removably connected at a medial portionbetween said sub-units by a common jacket material.
 10. The compositecable unit of claim 9, said at least one optical fiber including atleast one periodic refractive index therein.
 11. The composite cableunit of claim 9, said at least one electrical conductor being part of acoaxial cable.
 12. The composite cable unit of claim 9, said commonjacket material including a ligature connecting said sub-units.
 13. Thecomposite cable unit of claim 9, said sub-units being separably weldedtogether.
 14. The composite cable unit of claim 9, said common jacketmaterial including at least one identification means.
 15. The compositecable unit of claim 9, a controlled bond being formed between saidcommon jacket material and said at least one electrical conductor.
 16. Acomposite cable unit, comprising: an optical sub-unit, said opticalsub-unit including a tube surrounding at least one optical fiber andstrength members or filaments that are operative to at least partiallyde-couple said at least one optical fiber from said tube; an electricalsub-unit, said electrical sub-unit being a portion of a coaxial cable;and said optical and electrical sub-units being removably connected at amedial portion between said sub-units by a common jacket material. 17.The composite cable unit of claim 16, said at least one optical fiberbeing tight buffered.
 18. The composite cable unit of claim 16, saidcommon jacket material including a ligature connecting said sub-units.19. The composite cable unit of claim 16, said common jacket materialincluding at least one identification means.
 20. The composite cableunit of claim 16, a controlled bond being formed between said commonjacket material and a portion of said coaxial cable.